[Paraview] What part of the pipeline is producing the request for UPDATE_EXTENT?

[Moreland, Kenneth]

I belive it is supposed to work that your SetVOI() method should call modified, which will in turn cause the pipeline to call RequestInformation() on the next update.  Make sure that SetVOI() is actually calling Modified().

-Ken


On 2/12/08 9:26 PM, "Mike Jackson" <imikejackson at gmail.com> wrote:

Pretty sure that was where we were going to end up BUT as far as I
can tell, the order of execution is :
RequestInformation()
SetVOI() // From the GUI in ParaView
RequestData();

So we never really get a chance to get the VOI until RequestData
fires.. Is that what you have seen?

Mike
On Feb 12, 2008, at 11:21 PM, Kent Eschenberg wrote:

> Mike,
>
> I accomplished what you want with one of our custom readers. In my
> opinion the documentation for RequestInformation, RequestData,
> extents, etc. is so poor that it is useless.
>
> At RequestInformation I read enough of the input to get the overall
> input array size; apply the user-selected VOI; and return the
> desired subset as the whole extent. At RequestData I read the rest.
> I just don't bother letting VTK/ParaView manage the selection of
> the VOI. This has worked for 2.6.1 through 3.2.1.
>
> Kent
> Pittsburgh Supercomputing Center
>
> Mike Jackson wrote:
>> I can do that but I don't think it will work.
>> In paraview, I have managed to set an auto-generated UI for the
>> VOI. Now, the user opens our file, RequestInformation is run (I
>> can put some sane defaults for the VOI) and things are ok so far.
>> Now the user clicks "Apply" and then SetVOI is called with the
>> values from the GUI and then RequestData() is called after that.
>> So where do I update WHOLE_EXTENT? Or just take the values from
>> the VOI, create a vtkImageObject from that, and then just
>> ShallowCopy to the output object?
>> I'm a bit confused at this point. If our case is NOT a standard
>> use case for the pipeline than I guess I can look more seriously
>> into developing a full blown Plugin for our data file.
>> Mike


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